Synthesis 2021; 53(17): 3001-3010
DOI: 10.1055/a-1502-3641
special topic
Bond Activation – in Honor of Prof. Shinji Murai

Palladium-Catalyzed C–H Benzannulation of Functionalized Furans and Pyrroles with Alkynes

Jia Seo
a   Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea
,
Che-Wei Chen
b   Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
c   Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
,
Woohyeong Lee
a   Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea
,
Ju Eun Jeon
a   Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea
,
Pei-Ling Chen
d   Department of Chemistry, National Tsing Hua University, Hsinchu 30044, Taiwan
,
b   Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
c   Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
,
Jung Min Joo
a   Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea
› Author Affiliations
This work was funded by the National Research Foundation of Korea (NRF-2019R1A2C1007852 and NRF-2019R1A4A1028007) and the Ministry of Science and Technology of Taiwan (MOST108-2113-M009-020-MY3).


Abstract

A benzannulation strategy involving activation of two C–H bonds of five-membered heteroarenes was developed. Readily available furans and pyrroles stabilized by synthetically useful electron-withdrawing groups underwent Pd-catalyzed 1:2 annulation reactions with diaryl alkynes. A variety of functional groups, including ester, amide, ketone, aldehyde, and nitrile, on the heterocyclic cores were tolerated in the Pd-catalyzed oxidative reactions. In these reactions, the combination of 2,2-dimethylbutyric acid and its conjugate base facilitated metalation at the heteroaromatic rings and reoxidation of the Pd(0) species using oxygen as the terminal oxidant. This strategy provides fluorescent ­benzofuran and indole derivatives and is expected to allow for further development of functionalized polycyclic heteroaromatic compounds.

Supporting Information



Publication History

Received: 13 March 2021

Accepted after revision: 06 May 2021

Accepted Manuscript online:
06 May 2021

Article published online:
31 May 2021

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